1. Field of the Invention
Broadly speaking, this invention relates to filtration. More particularly, in a preferred embodiment, the invention relates to methods and apparatus for improving the efficiency of rotary disc filters, and the like.
2. Discussion of the Prior Art
Rotary disc filters are widely used in industry to separate solids or semi-solids from liquids, such as water. For example, disc filters are used to separate wood pulp from water or to separate minerals, such as taconite, copper, coal, and cement, from other carrier liquids.
As discussed in U.S. Pat. No. 4,086,168 issued Apr. 25, 1978 and assigned to the same assignee as the present invention, which patent is hereby incorporated by reference as if more fully set forth herein, prior art disc filters suffer from the problem of clogging of the discharge chutes. This clogging is due to the fact that the filtered solid material, called "cake" in the industry, is typically very tacky and tends to adhere to itself and to the walls of the discharge chute. The solution to the above problem which is disclosed in the above-referenced U.S. Pat. No. 4,086,168, i.e., a replaceable, plastic, chute liner with very smooth sides, has been highly successful in practice. Nevertheless, because this liner is constrained by the preexisting geometry of the discharge chute, under certain circumstances clogging of the discharge chute can still occur. This same geometry also permits the cake to work its way between the liner and the walls of the discharge chute, which also causes clogging.